The present invention relates to a heat alarm for an electric panel cabinet. More specifically, the present invention relates to a battery powered heat alarm that includes a microprocessor controller that extends the life of the battery.
Electric panel cabinets typically house the main electric service panels or subpanels for the electric supply to a residential or commercial building. Electric panel cabinets typically contain many components that may overheat and start fires, such as feeder conductors, branch circuit conductors, circuit breakers, fuses, and bus bars. The overheating of one of these electrical components within the electric panel cabinet can be caused by many types malfunctions, such as loose or corroded connections, power overloads, or other malfunctions in the components themselves. When one of these electric components malfunctions, the large amount of voltage and current flowing through the components causes heat buildup within the cabinet and ultimately can ignite a fire within the cabinet, which then may spread to nearby building structural components and create a fire hazard.
Although smoke alarms are required to be in every residential or commercial building by the majority of local building codes, these smoke alarms often do not provide adequate protection against fires started in the electric panel cabinets. Specifically, smoke alarms are often not located near the electric panel cabinet, since the electric panel cabinet is typically located in a remote area of the building away from the normally occupied areas. Even if a smoke alarm is located near the electric panel cabinet, the smoke alarm typically reacts only after a fire has started and a sufficient amount of smoke has been produced. In an electric panel cabinet, an overheat condition may exist for hours or even days before smoke is present to trip a smoke alarm. Additionally, since many smoke alarms in commercial buildings are connected to the building's electrical system, a fire started in the electric panel cabinet can cause a loss of electric power, which then disables the smoke alarm.
Altavela et al. U.S. Pat. No. 5,461,367 teaches an electric panel heat alarm that responds to an overheat condition within an electric panel cabinet. The heat alarm disclosed in the '367 patent positions a heat sensor within the enclosed area defined by the cabinet and uses a battery power supply to activate an audible alarm when the temperature within the electric panel cabinet exceeds an upper temperature limit. While the alarm disclosed in the '367 patent operates sufficiently to indicate an overheat condition in the electric panel cabinet, the alarm of the '367 patent suffers from several drawbacks. Specifically, the alarm of the '367 patent is operated by a 9 volt battery in the event of an external power failure. If an overheat condition exists in the electric panel cabinet and the external power has been disrupted, the 9 volt battery continuously operates the audible alarm. However, since the audible alarm draws a relatively large amount of current when operating, the continuous operation of the audible alarm drains the battery power supply in a relatively short amount of time. Thus, if the home/business owner is away from the building, the audible alarm may not be heard before the battery power supply is completely drained. Because of the short battery life, the alarm disclosed in the '367 patent may fail to indicate to the home/business owner that an overheat condition exists in the electric panel cabinet.
It is therefore an object of the present invention to provide a heat alarm that responds to an overheat condition in an electric panel cabinet by activating an audible alarm. It is a further object of the invention to operate the audible alarm in a manner such that the life of the battery power supply is sufficiently extended such that the heat alarm notifies the home/business owner of the overheat condition even if the home/business owner is not present when the alarm initially activates.
It is a further object of the invention to provide a heat alarm having an override feature that allows the home/business owner to interrupt the activation of the audible alarm for an override period such that the home/business owner can attempt to remedy the overheat condition while the audible alarm is deactivated, thereby extending the battery life. It is another object of the invention to provide a visual indicator that continuously indicates that the electric panel is in an overheat condition, even during the override period when the audible alarm is deactivated.